Final answer:
To allow VM1 to access Storage1 using a private IP address within an Azure subscription, Azure Private Link should be used. It enables private connections between Azure services and VNet, giving Storage1 a private IP within the VNet.
Step-by-step explanation:
To ensure that Virtual Machine (VM1) can access Storage Account (Storage1) using a private IP address within an Azure subscription, the correct service to use is Azure Private Link. Azure Private Link provides a secure and private connection between Azure services and your virtual network (VNet), effectively bringing the service into your VNet. The service you access through Azure Private Link, such as an Azure Storage account, gets a private IP address from the VNet address space, making it part of the VNet.
Other options mentioned, such as Azure Virtual Network, Azure Load Balancer, and Azure Traffic Manager, do not directly provide the capability to connect a VM to a storage account over a private IP. An Azure Virtual Network enables VMs to communicate privately with each other, but on its own, it doesn't provide direct access to a storage account. Azure Load Balancer distributes network traffic across multiple servers, which is different from securing private connectivity to a service. Azure Traffic Manager controls the distribution of user traffic for service endpoints in different datacenters, which is more about DNS and traffic routing rather than providing a private connection.
Using Azure Private Link allows VM1 and Storage1 to communicate over the Azure backbone network, avoiding exposure to the public internet. This service helps in enhancing security and potentially reducing latency as the data travels within the Azure infrastructure.